Confusion is bigger than surprise. First that Yurio throws something at him, eliciting a sound of that confusion. A brown paper bag. That lands on his lap. Not heavy, but definitely not empty. The faintest of spots around the bottom, and whatever it's holding. But the rest is even more confusing.

Because Yurio mentions his birthday, which is as true as it's not, there's still time, but it leaves him startle-struck, only able to elicit another confused sound, by the confusion of the word birthday. How does Yurio know when his birthday is? Why was he just handed something, framed as a birthday gift, by Yurio, who is now doing his best to not even look at him?

Shock has him finally picking up his chill-soaked hands, curling toward the bag and opening that flap.
Tipping the bag forward so he can look into it, not expecting what's inside it either. "Pirozhki?"